Mechanical properties of austenitic stainless steel with high niobium contents

To better understand the influence of the microstructural characteristics on the mechanical properties of Fe-Cr22-Ni25-Nbxaustenitic stainless steel (ASS-Nbx), the mechanical properties were investigated. Nb addition was conducted with four different amounts: 0, 0.29, 0.58 and 0.86%. With the increasing Nb content, the mean grain size for the Fe-Cr-Ni-based alloys decreased, while the size of Nb precipitate increased. Owing to the different microstructural characteristics, their mechanical properties were altered. The highest tensile strength was obtained for ASS-Nb0.29alloy. However, with the increasing Nb content in ASS-Nb0.29–0.86alloys, the tensile strength decreases despite the grain refinement. The mechanical properties of the ASS-Nb alloys were influenced by the Nb precipitation hardening and the grain boundary cohesive strength, arising from the size of Nb precipitations.